Natural-looking skin is influenced by a number of physiological and genetic factors. Standard definitions of beautiful skin include skin having a transparent quality with uniform undertones of color (e.g., rosy red cheeks). The basis of this natural-looking appearance is the skin structure itself. The outer layer of human skin is a semi-transparent layer termed the stratum corneum. The transparency of the stratum corneum permits observation of the deeper layers of skin, where blood vessels and pigments reside. The reddish hue of hemoglobin in the blood, and the brown/black hue of melanin, the primary skin pigment, combine to produce the skin color of an individual. In addition to skin having a transparent look with a uniform underlying color distribution, an ideal skin also should be smooth and even, with no apparent surface flaws. Very few individuals meet the ideal skin standard, therefore most individuals require assistance in the form of cosmetic compositions. Thus, a wide variety of “makeup” compositions have been developed to improve skin appearance.
Traditional makeup is not designed to mimic the natural appearance of beautiful skin, but is applied to the skin to mask skin imperfections. Currently, the trend in cosmetic composition is to provide a more natural-looking skin appearance. In particular, a long-sought goal is the development of a cosmetic composition that does not give the user a “made-up” look. However, it has been difficult to accomplish the goal of overcoming skin flaws and uneven skin tone, while maintaining the vibrant look of clean, bare skin. This difficulty is attributed primarily to opaque components typically included in cosmetic compositions, such as the titanium and iron oxide pigments, that provide the desired color and skin coverage, but obscure a vibrant skin transparency. Transparent pigments recently have become available, but the coverage needed to mask flaws in the skin surface frequently is lacking.
Personal care compositions have addressed the reduction of skin imperfections and the visible signs of aging, e.g., fine lines and wrinkles, using two major approaches. The first approach uses various bioactive antiaging ingredients. The second is a physical approach using inorganic materials to mask the appearance of fine lines and other skin imperfections. The second approach used is known as “soft focus” technology, which is based on the principle of scattered light. A recent third approach is to combine light scattering with fluorescent light emission. The emitted light illuminates the shadows in skin imperfections and provides an illusion that the imperfections do not exist.
The use of fluorescent brightener compounds in a cleansing and cosmetic compositions is known. U.S. Pat. No. 4,032,263 discloses a bleaching and brightening detergent composition containing an anionic and/or nonionic detergent, a builder salt, a peroxymonosulfate bleaching agent, a bromide bleaching promoter, and one or more optical brighteners that are stable in the presence of the bleach and the promoter.
U.S. Pat. No. 4,752,496 discloses a method of applying cosmetic ingredients to a substrate. The cosmetic ingredients are combined with a liquid carrier and film-forming agent, and deposited onto a substrate. The film-forming agent microencapsulates the cosmetic ingredients, and, after drying, protects the cosmetic ingredients. The protected cosmetic ingredients then can be applied to a substrate and covered with a paperboard sheet.
U.S. Pat. No. 6,117,435 discloses “natural-look” cosmetic compositions. These topical compositions for application to the skin contain silica beads having an inner silica core, a middle metal oxide layer, and an outer silica layer; at least one interference pigment; and, optionally, at least one noninterference pigment, in a cosmetically or pharmaceutically acceptable formula. The cosmetic compositions impart a natural appearance to the skin, while reducing the appearance of skin flaws or defects without an opaque or made-up appearance.
U.S. Pat. No. 6,194,375 discloses a perfume absorbed within polymeric particles that further have a polymeric coating on the particle surface. The polymer on the particle surface can be part of an encapsulating shell, and can be highly hydrolyzed polyvinyl alcohol (PVA). U.S. Pat. No. 6,204,033 discloses spherical PVA polymer particles that encapsulate a magnetic colloid for use in binding biomolecules. WO 94/28223 discloses nonwoven articles comprising a nonwoven web of organic fibers and a binder comprising at least partially cross-linked by a resin having a plurality of hydroxy groups.
Optically activated particles containing a fluorescent brightener fixed to a microporous nylon-12 powder core, and encapsulated in a polyoxymethylene urea (PMU) shell, are commercially available as LipoLight™ OAP/C from Lipo Chemicals, Inc., Paterson, N.J. The fluorescent intensities of the PMU encapsulated particles are about twice that of identical, but nonencapsulated, particles. The encapsulated particles are used to reduce the perception of skin imperfections. However, the PMU shell poses environmental and toxicity concerns because the presence of free formaldehyde. Accordingly, researchers have investigated particles that eliminate the use of PMU, while retaining the efficacy required to reduce the appearance of skin imperfections.
Accordingly, a need remains in the art for cosmetic compositions capable of imparting a perception that human skin has fewer wrinkles and other imperfections, e.g., cellulite, generates an even skin tone, obscures discolorations of the skin, and/or reduces skin blotchiness. The optically activated particles of the present invention meet this need by emitting and reflecting visible light, and increasing the diffusion of light. There also is a need to provide improved optically activated particles that overcome the disadvantage associated with prior optically activated particles.